1. Field of the Invention
The present invention generally relates to a display device. More particularly, the present invention relates to an electronic ink display device.
2. Description of Related Art
The electronic ink display device was developed in the 1970s. One of the major characteristic of the display device is incorporation of electrically charged micro-spheres with half of it being painted with white color and the other half being painted with black color. When an electric field is adjusted, the sphere will rotate top to bottom and hence display a different color. In the second generation of electronic ink display device developed in the 1990s, mini capsules have replaced the micro-spheres. Colored oil and charged white particles fill the mini capsules. The white particles can move to the top or sink to the bottom under a controlled electric field. When the white particles rise to the top (move closer to the reader), a white color is displayed. On the other hand, when the white particles sink to the bottom (away from the reader), the color of the oil is displayed.
At present, the most common electronic ink display device includes a frontplane laminate (FPL) and a thin film transistor array substrate. The frontplane laminate has a transparent electrode layer and an electronic ink material layer. The electronic ink material layer has a plurality of mini capsules (the electronic ink) and each mini capsule contain black and white color paint, and a transparent fluid. When the electric field between the pixel electrode of the thin film transistor array substrate and the transparent electrode layer changes, the paint will move up or down according to the direction of the electric field so that a black or a white color will appear in various pixels.
FIG. 1 is a schematic cross-sectional view of a part of the thin film transistor array substrate of a conventional electronic ink display device. As shown in FIG. 1, the thin film transistor array substrate 100 of a conventional electronic ink display device is fabricated by forming an indium tin oxide (ITO) layer 120 over a substrate 100. Then, a plurality of sources/drains 132/134 (only one is shown in FIG. 1) is formed over the indium tin oxide layer 120, and an ohmic contact layer 140 is formed over the source/drain 132/134. Thereafter, an etching solution is used to remove the oxide material on the substrate 100. After that, a channel layer 150 covering the ohmic contact layer 140 and a dielectric layer 160 covering the channel layer 150 are formed in sequence. Next, a plurality of gates 170 (only one is shown in FIG. 1) is formed over the dielectric layer 160. A passivation layer 180 is formed over the gates 170. Then, a resin layer 190 is formed to cover the substrate 110. Thereafter, an electrode layer 195 is formed over the resin layer 190. The electrode layer 195 is electrically connected to the indium oxide layer 120 through an opening 192 in the resin layer 190.
It should be noted that the thin film transistor array substrate 100 has a complicated structural design. Therefore, the manufacturing the thin film transistor array substrate 100 is quite time-consuming and expensive. As a result, the cost of producing the electronic ink display device also increases.